Solving Quadratics by Factoring and Graphing

bobbym · 2011-08-01 02:29:55

Correct!

zee-f · 2011-08-01 02:32:30

i got the following for #8-

roots -6,-5

(x+6)(x+5)=x^2+11x+30

anonimnystefy · 2011-08-01 02:32:52

very good!!!

Last edited by anonimnystefy (2011-08-01 02:33:01)

bobbym · 2011-08-01 02:33:00

Correct!

zee-f · 2011-08-01 06:16:53

thank you alot for the help guys this is the last one by graphing

i got -5,6

(x+5)(x-6)

x^2-1x-30

bobbym · 2011-08-01 06:19:00

That is correct!

zee-f · 2011-08-01 06:28:05

thank you alot alllot allllot both for the help

zee-f · 2011-08-01 06:32:37

i have a question if they give me a two roots and they want me to Work backwards to write a quadratic equation with the two roots that they give me how do i do it is it the same way ?

bobbym · 2011-08-01 06:32:45

Your welcome!

zee-f · 2011-08-01 06:37:29

i have a question if they give me a two roots and they want me to Work backwards to write a quadratic equation with the two roots that they give me how do i do it is it the same way ?

bobbym · 2011-08-01 06:38:46

What is a two roots?

zee-f · 2011-08-01 06:40:52

no like this is what the question says Work backwards to write a quadratic equation that will have solutions of x = 3 and x = -7. and this is what i did

(x-3)(x+7)= x^2+4x-21

is that correct ?

bobbym · 2011-08-01 06:43:00

Yes, that is correct.

zee-f · 2011-08-01 07:15:34

hey :)

ok and for these this is what i did hope i did them right

11. Work backwards to write a quadratic equation that will have solutions of x = 12 and x = 2.

11- x=12 x=2

(x-12)(x-2)= ((x^2-14x+24))

12. Work backwards to write a quadratic equation that will have solutions of x = -1/2 and x = 4.

12- x= -1/2 x=4

(x+1/2)(x-4) = (x^2-7/2x-2)

13. Write a quadratic equation that will have a solution of only x = 0. Note: this means there will be a double solution of x = 0..

13- x=0 x=0

(x-0) (x-0) = (x^2+0x+0)

zee-f · 2011-08-01 07:26:57

/

anonimnystefy · 2011-08-01 07:29:54

everything is correct.brilliant!

zee-f · 2011-08-01 07:33:27

thank you

zee-f · 2011-08-01 07:34:28

i have a question are there quadratic equation that cannot be factored?

anonimnystefy · 2011-08-01 07:49:50

surely there are.that is a very good question.

every quadric equation can be factored,but only in a certain field of numbers.so you can factor x^2+2x+1 in the field of integer, rationals,or real numbers.but x^2+x+1 cannot be factored in any of these fields,it can only be factored in the field of complex numbers.

zee-f · 2011-08-01 10:23:00

thank you soooo much anonimnystefy

can anybody help me with the following please really confused

16. The product of two consecutive negative integers is 10506. Write a quadratic equation that you could solve to find the integers.

zee-f · 2011-08-01 11:02:36

16. The product of two consecutive negative integers is 10506. Write a quadratic equation that you could solve to find the integers.

bobbym · 2011-08-01 17:20:24

Hi zee-f;

That is the quadratic you want.

zee-f · 2011-08-02 10:43:08

hey guys this is what i did i need help checking if i did it correct

14. Write a quadratic equation that cannot be factored.

14-x^2+x+3=0

15. The product of two consecutive positive integers is 72. Find the integers.

#15- n(n+1)=72

n^2+n-72=0

-72+n+n^2=0

(-9+-1n)(8+-1n)=0

-9+-1n=0

-9+9-1n=0+9

-1n=9

n=-9

8+-1n=0
8+-8+-1n=0+-8

-1n=-8
n=8

n=-9,8

16. The product of two consecutive negative integers is 10506. Write a quadratic equation that you could solve to find the integers.

16- n(n+1)=10506

n^2+n-10506=0

-10506+1n+n^2=10506+-10506

-10506+1n+n^2=0

(-103+-1n)(102+-1n)=0

-103+-1n=0

-1n=0+103

-1n=103

n=-103

102+-1n=0

102+-102+-1n=0+-102

-1n=0+-102

-1n=-102

n=102

17. The product of two consecutive odd integers is 63. Write a quadratic equation that you could solve to find the integers, then find the integers.

(reallllly confused ))))

bobbym · 2011-08-02 14:19:46

Hi;

14) is correct.

15) Is not correct. You were asked for 2 consecutive positive integers. Disregarding the -9, it is not positive, the answers are 8 and 9. And check your answer.

16) Is correct!

17) Do not be confused! Here is a really big hint for doing school problems. Always remember that all the problems they give are all the same, one way or another. The same method that has been working, will continue to work.

Call n the first odd number you want. All consecutive odd numbers differ from each other by 2. For instance, if 3 were your number then the next odd number is 5. If 11 was your number then the next odd number is 13. So if n is your odd number then the next odd number is ( n + 2 ).

They ask for a product, so that means you multiply the two numbers as you already know.

n ( n + 2 ) = 63

zee-f · 2011-08-03 09:37:16

hey

for #15

8+-1n=0

8+-8+-1n=0+-8

-1n=-8

n=8

9+-1n=0

9+-9+-1n=0+9

-1n=-9

n=9

n=9,8

#17- n(n+2)=63

n(2+n)=63

2n+n^2=63

-63+2n+n^2=63+-63

-63+2n+n^2=0
(-9+-1n)(7+-1n)=0

-9+-1n=0
-9+9+-1n=0+9

-1n=9

n=-9

7+-1n=0
7+-7+-1n=0

-1n=-7

n=7

Math Is Fun Forum

#151 2011-08-01 02:29:55

Re: Solving Quadratics by Factoring and Graphing

#152 2011-08-01 02:32:30

Re: Solving Quadratics by Factoring and Graphing

#153 2011-08-01 02:32:52

Re: Solving Quadratics by Factoring and Graphing

#154 2011-08-01 02:33:00

Re: Solving Quadratics by Factoring and Graphing

#155 2011-08-01 06:16:53

Re: Solving Quadratics by Factoring and Graphing

#156 2011-08-01 06:19:00

Re: Solving Quadratics by Factoring and Graphing

#157 2011-08-01 06:28:05

Re: Solving Quadratics by Factoring and Graphing

#158 2011-08-01 06:32:37

Re: Solving Quadratics by Factoring and Graphing

#159 2011-08-01 06:32:45

Re: Solving Quadratics by Factoring and Graphing

#160 2011-08-01 06:37:29

Re: Solving Quadratics by Factoring and Graphing

#161 2011-08-01 06:38:46

Re: Solving Quadratics by Factoring and Graphing

#162 2011-08-01 06:40:52

Re: Solving Quadratics by Factoring and Graphing

#163 2011-08-01 06:43:00

Re: Solving Quadratics by Factoring and Graphing

#164 2011-08-01 07:15:34

Re: Solving Quadratics by Factoring and Graphing

#165 2011-08-01 07:26:57

Re: Solving Quadratics by Factoring and Graphing

#166 2011-08-01 07:29:54

Re: Solving Quadratics by Factoring and Graphing

#167 2011-08-01 07:33:27

Re: Solving Quadratics by Factoring and Graphing

#168 2011-08-01 07:34:28

Re: Solving Quadratics by Factoring and Graphing

#169 2011-08-01 07:49:50

Re: Solving Quadratics by Factoring and Graphing

#170 2011-08-01 10:23:00

Re: Solving Quadratics by Factoring and Graphing

#171 2011-08-01 11:02:36

Re: Solving Quadratics by Factoring and Graphing

#172 2011-08-01 17:20:24

Re: Solving Quadratics by Factoring and Graphing

#173 2011-08-02 10:43:08

Re: Solving Quadratics by Factoring and Graphing

#174 2011-08-02 14:19:46

Re: Solving Quadratics by Factoring and Graphing

#175 2011-08-03 09:37:16

Re: Solving Quadratics by Factoring and Graphing

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